291691 has 2 divisors, whose sum is σ = 291692. Its totient is φ = 291690.

The previous prime is 291689. The next prime is 291701. The reversal of 291691 is 196192.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 291691 - 2¹ = 291689 is a prime.

Together with 291689, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (291661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 145845 + 145846.

It is an arithmetic number, because the mean of its divisors is an integer number (145846).

2²⁹¹⁶⁹¹ is an apocalyptic number.

291691 is a deficient number, since it is larger than the sum of its proper divisors (1).

291691 is an equidigital number, since it uses as much as digits as its factorization.

291691 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 972, while the sum is 28.

The square root of 291691 is about 540.0842526866. The cubic root of 291691 is about 66.3194643418.

It can be divided in two parts, 2916 and 91, that multiplied together give a triangular number (265356 = T₇₂₈).

The spelling of 291691 in words is "two hundred ninety-one thousand, six hundred ninety-one".